On Sunday, January 11th, almost 4 million people across France and several hundred thousand more globally, marched in solidarity against terrorism. The biggest gathering was in Paris where an estimated 1.7 million people, including 40 world leaders, walked along the boulevards and avenues of central Paris. Some were carrying signs with the slogan “Je suis Charlie” (I am Charlie), while others held up large stylized pencils or wore writing implements on their hats or other items of clothing.

All the symbols were a tribute to satirical magazine publisher Charlie Hebdo, where the event that terrorized the nation for three days, began. On Wednesday, January 7th, two gunman stormed into the Paris office of Charlie Hebdo and killed 12 people, including two police officers, as well as the magazine's chief editor, Stephane 'Charb' Charbonnier. The assassinations conducted by brothers Cherif and Said Kouachi who had links to Islamic terrorist group Al Qaeda, are believed to be a response for the magazine's numerous mocking cartoons depicting prophet Muhammad, a strict taboo in Islam. The tragedy did not end there.

Despite efforts to stop them, the two escaped. On January 8th, with the police close on their tracks the terrorists hid inside a small printing plant in Dammartin-en-Goele, northeast of Paris, holding its manager hostage.

If that was not bad enough, an eerily similar scenario was unfolding in a different part of the city at about the same time. Another terrorist, Amedy Coulibally, who authorities believe was connected to Cherif and Said Kouachi, began by killing an unarmed police officer that was responding to a traffic incident in the southern Paris suburb of Montrouge. The following day, just a few hours after the Kouachi brothers took over the printing press, he barricaded a kosher supermarket nearby, with a number of customers still inside.

On Friday, January 9th, the French police stormed both places almost simultaneously, successfully killing all three terrorists. While the manager of the printing press escaped unscathed, four supermarket customers held captive by Amedy Coulibally, were not as lucky.

To pay tribute to the 17 people that perished and demonstrate the country's unity against anyone that threatened their basic right of freedom, a group of residents decided to organize a march. They adopted the slogan "Je Suis Charlie", which soon went viral, becoming the most popular news hashtag in Twitter history, within two days. Not surprisingly, the march soon took on a life of its own, ending up as one of the biggest gatherings in the country's history.

People all across the world, from Berlin to London, New York to Sydney, showed support for France's determination to stand up to terrorism by holding similar marches in their cities. As for the publishers at Charlie Hebdo? Despite the major setback, they immediately got back to work. This week's magazine cover depicts Prophet Muhammad holding a "Je suis Charlie" sign - a clear indication that they are not going to let anyone dictate what they can or cannot publish in their magazine.

Resources: latimes.com, dailymail.co.uk,nbcnews.com, cnn.com